Happy birthday, you big old eye in the sky! On Tuesday, April 24, the Hubble Space Telescope will celebrate 28 years in space. Since its launch in 1990, it has revolutionized almost every area of observational astronomy and provided us countless photos of the most amazing objects in space. Since we can’t bring a birthday cake up there, each year partners ESA and NASA celebrate the telescope’s birthday with a spectacular new image. This year’s photo is of the Lagoon Nebula, a glowing cloud of star-shot, hydrogen gas and one of the few visible with the naked eye.
The Lagoon is a colossus. 55 light-year wide and 20 light-years tall, that’s more than twice the distance from here to the bright star Vega, now peeping above the northeastern horizon at 10 o’clock. Even though it’s about 4,000 light-years away from Earth, the Lagoon has a surprisingly large “footprint” in the sky — 1.5° across or three times larger in apparent size than the full moon. Because it’s so big, Hubble’s narrow-ish field of view could only capture the innermost 4 light years, the “heart” of the nebula.
The Lagoon got its name for the broad, dark lane of cosmic dust that winds through the bright gases. Like a real lagoon, it has a black, murky quality to it. Careful! Take a false step, and you might fall in. The dust is silhouetted against a background of hydrogen gas excited to glow red from large, hot, newborn stars that recently emerged from the nebula’s nooks and crannies. Their ultraviolet light ionizes or energizes the surrounding atoms; when the atoms “relax” moments later, they emit a pink light characteristic of many nebulae, including the more familiar Orion Nebula.
Both UV radiation and powerful winds of subatomic particles blowing from these giants sculpts the gas and dust into bizarre and other-worldly shapes. The bright star embedded in dark clouds at the center of the image is called Herschel 36. Its radiation sculpts the surrounding cloud by blowing some of the gas away, creating dense and less dense regions.
The dark, twisted shapes near Herschel 36 are called interstellar twisters — each measures half a light-year in length. Like their namesakes on Earth, they’re thought to be coiled into funnel-like shapes by temperature differences between the hot surfaces and cold interiors of the clouds. At some point in the future, these clouds will collapse under their own weight and give birth to a new generation of stars.
Hubble can observe in both visible and infrared light. Visible light reveals the myriad dust clouds that sculpt the Lagoon, while infrared light cuts through that dust and gas, exposing hundreds of young stars that hide within. By studying the nebula in both types of light, astronomers can appreciate the lagoon’s true nature as an incubator of new stars … and planets, comets and asteroids. No matter where you look, nature is either busy building or taking apart.
The Lagoon is one of the brightest nebulae in the sky and visible right now in the morning sky before the start of dawn in the constellation Sagittarius. From a dark sky site, it looks like a fuzzy patch of light with the naked eye, but use binoculars (or a telescope) for the best view. If you can find the bright pair of planets, Mars and Saturn, you’re almost there. Saturn is to right of Mars. Point your binoculars at Saturn, focus and then slide 8° (almost one “fist”) due west of the planet, and you’ll see a twinkles of starlight tangled in haze. You have arrived!
** A special reminder to readers who live in the Duluth area. I’ll be signing my new book Wonders of the Night Sky You Must See Before You Die at Barnes & Noble in the Miller Hill Mall in Duluth from noon to 3 p.m. this Saturday, April 21. Do stop on by and say “hi.” I’m looking forward to meeting you!